Digital to analog converter
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorMasao Arimoto
Life of this patent
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Abstract
A D-A converter in which a phase deviation in load current is inhibited and a digital to analog conversion accuracy is enhanced. A data dividing block (7) is provided to switch a path depending upon a value of the most significant bit of an N bit digital signal (DATA) so as to conduct the D-A converting and the V-I converting based upon an (N-1)bit digital signal (DATA(N-1)) in either one of a first analog current output path consisting of a D-A converting block (11) and a V-I converting unit (210) and a second analog current output path consisting of a D-A converting block (12) and a V-I converting unit (220). Thus, since a large range of load current can be obtained and a phase deviation in the load current can be inhibited, a D-A conversion accuracy is enhanced.
Claims7
A D-A converter comprising:
- digital data dividing means, having first and second outputs and receiving an N bit digital signal, for outputting from the first output partial digital data which is (N-1) bit digital data obtained by eliminating the most significant bit from said digital signal, and outputting from the second output fixed digital data;
- first D-A converting means connected to said first output of said digital data dividing means for D-A converting said digital data received from said first output to output a first analog voltage;
- second D-A converting means connected to said second output of said digital data dividing means for D-A converting said digital data received from said second output to output a second analog voltage;
- first voltage to current converting means receiving said first analog voltage for voltage to current converting said first analog voltage to output a first analog current;
- second voltage to current converting means receiving said second analog voltage for voltage to current converting said second analog voltage to output a second analog current;
- and
- current synthesizing means for synthesizing said first analog current and said second analog current to output synthetic analog current;
- wherein said first voltage to current converting means includes:
- a first operation amplifier for receiving said first analog voltage on its positive input,
- a first resistance having its first terminal connected to a negative input of said first operational amplifier and its second terminal connected to first supply voltage, and
- a first transistor having its first electrode connected to said first terminal of said first resistance and its control electrode connected to the output of said first operational amplifier;
- and
- wherein said second voltage to current converting means includes:
- a second operational amplifier for receiving said second analog voltage on its positive input,
- a second resistance having its first terminal connected to a negative input of said second operational amplifier and its second terminal connected to a second supply voltage, and
- a second transistor having its first electrode connected to said first terminal of said second resistance and its control electrode connected to the output of said second operational amplifier;
- and
- the current synthesizing means is wiring for connecting the second electrode of said first transistor and the second electrode of said second transistor.
Dependencies are inferred from the claim text.